Use a different way for fetching resources that works on java 9 as well

src/nl/uu/cs/ssmui/HelpFromProp.java

@@ -34,7 +34,7 @@ public class HelpFromProp
 	
 	private static Properties getProps( String nm )
 	{
-		URL url = nm.getClass().getResource( "/Help/" + nm + ".prop" ) ;
+		URL url = HelpFromProp.class.getResource( "/Help/" + nm + ".prop" ) ;
 		Properties props = new Properties() ;
 		try
 		{

src/nl/uu/cs/ssmui/Images.java

@@ -32,7 +32,7 @@ public class Images
 	
 	private static ImageIcon getImage( String nm )
 	{
-		return new ImageIcon( nm.getClass().getResource( "/Images/" + nm + ".gif" ) ) ;
+		return new ImageIcon( Images.class.getResource( "/Images/" + nm + ".gif" ) ) ;
 	}
 	
 	static